Floor wastes for the drainage of waste water from bathroom shower recesses for example, are typically connected to the sewerage system via goose neck or “S” bend trap fitting designed to maintain a volume of water as a barrier between the floor waste and the sewer and thereby prevent the emission of sewer odours into the bathroom.
Although usually effective in the blockage of odours, the volume of water may not always be maintained to a sufficient level to block all air (and therefore odour) passage through the “S” bend trap and hence up through the waste outlet. In some situations, negative pressure downstream of the trap, can partially suck the water from the trap and thus allow odour to pass back up through the waste outlet. This is not an uncommon problem in multi-story installations where volumes of waste water fall through the common plumbing line; the passage of the water causing the suction at S bends at lower levels.
Some waste installations may occur in which there is no water trap, or the water trap is at considerable remove from the waste outlet so that odours and other undesirable effects may issue into the building.
It is an object of the present invention to address or at least ameliorate some of the above disadvantages.
Notes
    1. The term “comprising” (and grammatical variations thereof) is used in this specification in the inclusive sense of “having” or “including”, and not in the exclusive sense of “consisting only of”.    2. The above discussion of the prior art in the Background of the invention, is not an admission that any information discussed therein is citable prior art or part of the common general knowledge of persons skilled in the art in any country.